[Brett’s] version is a bit more robust than the one we featured the other day. It’s similar to [Dino’s] in that it uses a 555 timer in astable mode, triggered by a normally-closed microswitch when the tin is opened. However, this version also includes a photoresistor which is used to increase the pitch and speed of the output as more light enters the box. This creates a growling effect that builds up into a scream as the box is opened. [Brett] has also included an adjustable pot which allows the sound range to be tweaked to his liking.

Stick around for a video walkthrough of the screamer circuit as well as a demo of the Altoids tin in action.

6 thoughts on “Adjustable prank box growls and screams”

Thanks Dino! So far everyone jumps pretty good when they go for a mint and get a nice surprise ;-) The dark chocolate is too enticing!! Thanks for posting my article HAD, I’d like to see what other variations people can come up with… like using two 555’s, or a micro. You could get that modulated sound in any light with two 555’s, just run the modulator output into the CV (pin 5) input of the main tone generator. It would also be neat if one of those scary “inverted” faces pops out like this one: http://i51.tinypic.com/zmxjb4.jpg

Years ago an employee of DEC made a box like that and placed it in various places around the building. Everyone knew it was him since his initials were clearly printed on the box. That was until one day that a new security guard saw it….told his supervisor who said it wasn’t a problem….but went and called the bomb squad anyway….poor plant just wanted to live it’s life but got blown up.

@AF DEC Emp – Thanks for sharing ;-) I guess the moral of the story there is that if you want to disguise a bomb, don’t jam a bunch of electronics into something that shouldn’t have any. And under no circumstances should the bomb have any “coiled” wires coming out of it over to another part… and um, no duct tape!